Reciprocating pump



$- ZAHRADNIK RECIPROCATING PUMP Filed NOV. 15, 1968 Dec. 8, 1970 7\ m Ja??? A 4 h U 7% 3 A 5 4 l a m a z 1 VENTOR a/rraan/ United States PatentO 3,545,896 RECIPROCATIN G PUMP Stanislav Zahradnik, Roztoky uJilemnice, Czechoslovakia, assignor to Elitex, Zavody textilnihostrojirenstvi,

generalni reditelstvi, Liberec, Czechoslovakia Filed Nov. 13, 1968, Ser.No. 775,374

Claims priority, application Czechoslovakia, Nov. 15, 1967, 8,083/67Int. Cl. F04b 29/00 US. Cl. 417-471 7 Claims ABSTRACT OF THE DISCLOSUREA pump for discharging air in pulses of precisely controlled volume,velocity, and timing has a cylinder divided by an annular collar into aworking chamber and a lubricant chamber. A plunger passes through acylinder end wall into the lubricant chamber and thence through thecollar into the working chamber to draw air into the latter, and tocompress the air and discharge it through suction and pressure valvesrespectively. The plunger is guided in axially short, conforming boresof the collar and of the end wall which are protected against dust bythe lubricant which is held in the lubricant chamber under a pressurenormally higher than that of the working chamber.

BACKGROUND OF THE INVENTION .This invention relates to reciprocatingpumps, and

particularly to pumps suitable for discharging precisely O timed pulsesof compressed air having a closely controlled velocity and volume.

Pumps of the type described are employed in shuttleless jet looms forblowing a weft thread through the shed of warp threads. The preciseoperation of the pumps which produce the jet of air is essential to theoperation of the 100m, and deviations of the air jets or pulses fromprescribed values in any of their properties cause misweaves.

It is not normally practical to employ piston rings in such a pump. Thepiston is precisely ground and polished to match the bore of the pumpcylinder. The discharge stroke of the piston is brought about by therapid expansion of a spring compressed during intake, a more positivedrive of the piston being unsuited for the intended purpose.

The spring drive, however, is very sensitive to changes in thefrictional resistance of the piston. An increase in the piston frictionreduces the velocity at which air is discharged from the pump. Even whenan air filter is employed, it is unavoidable that small, solid particlesare airborne into the known pump and are lodged where they increasepiston friction. Moreover, minute metal particles are dislodged by wearfrom the slidingly engaged surfaces of the piston and pump cylinder, andfurther contribute to friction. It is therefore necessary in known pumpsfrequently to adjust the spring tension in order to compensate forincreasing friction, and to replace the pumps after relatively shortoperation periods for a thorough cleaning and overhaul. If a burdensomemaintenance schedule is not maintained, the spring may become unable tomove a sticking piston in the required manner, and costly defects may becaused in the woven material.

The known pumps used in jet looms also are quite sensitive totemperature. They do not perform in the same manner immediately afterstart-up when cold and after warming up, and only a careful andexperienced operator can avoid misweaves resulting from variation inoperating temperature. The temperature sensitivity of the known pumps isenhanced by the presence of accumulated solid contaminant particles inthe pump cylinder.

The primary object of the invention is the provision of a pump for a jetloom which, in effect, purges itself of solid contaminant particles, andwhose frictional resistance to the operating force of a spring does notchange materially over an extended operating period regardless of thetemperature of the ambient atmosphere or the pump itself.

SUMMARY OF THE INVENTION With this object and others in view, theinvention provides a pump whose cylinder cavity is axially divided intotwo chambers by a collar having a central bore. One of the chambers,hereinafter referred to as lubricant chamber, is axially bounded by anend wall of the cylinder formed with an axial bore therethrough. Aplunger conformingly engages both bores for axial sliding movement. Thetwo free axial ends of the plunger are respectively exposed in the otherchamber of the cylinder cavity, hereinafter referred to as the workingchamber, and outside that cavity. The plunger is reciprocated by thepump drive inward and outward of the working chamber, whereby thecontents of the latter are alternatingly compressed and expanded.

Suction and discharge valves on the cylinder are normally closed, andopen respectively in response to the outward and inward movements of theplunger for admitting fluid to the working chamber and for releasing thefluid. A lubricating system feeds lubricant to the lubricant chamber,the term lubricant being limited to a material having a viscositygreater than that of water. The lubricant pressure in the chamber isheld substantially above that of the ambient atmosphere.

The frictional resistance of the piston to its operation by a springdrive is held to a practically constant very low value by theafore-described use of a lubricant chamber and by specific dimensionalrelationships between the portions of the plunger which are confined inthe bores of the collar and of the end wall, and those which are exposedin the two chambers. For reasons which will be more fully explainedhereinafter, the surface area of the plunger exposed in the two chambersshould not be substantially smaller than the surface area confined inthe two bores in any operating position of the plunger during thereciprocating movement of the same. At the end of the compressionstroke, at least, the exposed surface area should be substantiallygreater than the confined area. More specifically, the axial length ofthe exposed surface should be much greater than the axial length of theconfined surface at the end of the compression stroke. For best resultsthe axial length of the bore in the collar must be substantially smallerthan the axial length of the working chamber.

Other features, additional objects, and many of the advantages of thisinvention will readily be appreciated from the following detaileddescription of preferred embodiments when considered in connection withthe appended drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 shows a reciprocating pump of the invention in elevationalsection at the end of its dischargre or compression stroke;

FIG. 2 shows the pump of FIG. 1 at the beginning of its discharge strokein a fragmentary view corresponding to that of FIG. 1; and

FIG. 3 shows a modified pump of the invention in a view corresponding tothat of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to FIG. 1,there is seen the pump of the picking mechanism in a jet-loom. The head1 and cylinder 2 of the pump are mounted between stationary elements ofthe loom frame 3, not otherwise shown, and a gasket 4 seals the head 1to the cylinder 2. A conically tapering check valve 5 is biased by aspring 7 to close a bore 6 in the head 1, which connects the cavity ofthe cylinder 2 with the ambient atmosphere, the valve being arranged toopen under a pressure in the cylinder cavity which exceeds atmosphericpressure by an amount determined by the characteristics of the helicalcompression spring 7.

An internal, annular, integral collar 8 divides the cavity of thecylinder 2 into a working chamber 9 and a lubricant chamber 10. The boreof the collar 8 has the same diameter as a bore in the end wall 11 ofthe cylinder 2 remote from the head 1. A cylindrical plunger 12 has afree end in the working chamber 9 and passes in conforming engagementthrough the bores in the collar 8 and the end wall 11. The free end ofthe plunger 12 outside the cylinder 2 carries a threadedly adjustableabutment ring 13, and extends inward of a cup-shaped, coaxial pushermember 14.

The rim of the member 14 is held in axially abutting engagement with thering 13 by a strong, helical compression spring 15, partly coiledcoaxially about the pusher member 14. The other axial end of the spring15 rests on a washer 16. The axial position of the washer may beadjusted by means of a bushing 17 threadedly received in the loom frame3 and coaxially engaging the washer 16 under the pressure of the spring15. The head of a long and slender bolt 18 is retained in the pushermember 14. Its shank passes freely through a central opening in thebottom of the member 14, the washer 16, and the bushing 17, and its freeend threadedly engages a nut 19 which is normally held against thebushing 17 by the spring 15.

A radial bore 20 passes through the wall of the cylinder 2 and thecollar 8. Another radial bore 21 in the cylinder wall terminates in theannular free space of the lubricant chamber 10. A rocker 22 is pivotedon the loom frame 3. One arm of the rocker 22 carries a sphericallyrounded stop 23 axially aligned with the free radial face of the ring13. The other arm follows the cam face of a radial cam 24 whose driveshaft 25 is coupled to the loom drive. The cam face of the cam 24extends approximately in an Archimedes spiral about the axis ofrotation, the two circumferential ends of the spiral being connected bya straight cam face portion which is almost radial.

The illustrated pump operates as follows:

When the continuously rotating cam 24 moves clockwise from the positionshown in FIG. 1, the plunger 12 is slowly retracted from the chamber 9by the rocker 22 toward the position seen in FIG. 2 in which the freeend of the plunger clears the bore 20, the air intake port of the pump.Withdrawal of the plunger 12 from the working chamber 9 creates apartial vacuum in the chamber which is broken when the Plunger opens toport 20.

The pressure of the rocker 22 on the ring 13 also causes the spring 15to be compressed. When the rocker 22 reaches the practically radial faceportion of the cam 24, the spring 15 is suddenly released and pushes theplunger 12 inward of the working chamber 9 until the bottom of thepusher member 14 strikes the head of the bolt 18 while the nut 19 abutsagainst the bushing 17. The port 21 is closed as the plunger 12 beginsits inward stroke, and the suddenly compressed air in the workingchamber 9 lifts the valve 5 from its seat in the head 1, and a briefblast of air is discharged through the bore 6 until the spring 7 canagain close the valve 5, whereupon another cycle begins.

The lubricant chamber 10 is normally filled with lubricating oil underpositive pressure, the bore 21 providing a lubricant port normallyconnected with other elements of the pressure lubrication system of theloom,

conventional in itself and not otherwise illustrated. The moving plunger12 maintains a lubricant film in the closely fitting bores of the collar8 and of the end wall 11. Dust unavoidably entering the port 20 even ifthe latter is provided with an air filter, not shown, is carried withlubricant into the working chamber 9 by the leading edge of the plunger12, dispersed there in a large excess of air, and harmlessly dischargedthrough the valved bore 6. No solid particles can enter the lubricantfilm in the bore of the end wall 11 from the atmosphere against thelubricant flow.

The friction of the plunger 12 in the guiding cylinder bores ispractically constant. It is changed only by the slow surface wear of theplunger 12 and the cylinder 2. With mating surfaces ground and polished,as is usual in pumps of this type, the Wear is very slow, and the metalparticles released from the frictionally engaged surfaces are harmlesslycarried off by the lubricant. The spring 15 need be adjusted veryinfrequently to maintain uniform performance of the pump. It isvirtually impossible for the plunger 12 to be stuck in the cylinder 2with a resistance that cannot be overcome by the spring 15, because theplunger engages the cylinder 2 over only a small fraction of its axiallength and the corresponding axial length of the chamber 9.

In actual use, pumps substantially identical with that shown in FIGS. 1and 2 have been found to operate reliably over extended periods atvarying temperatures of the ambient atmosphere and of the working partsof the pump. The temperature of the plunger 12 is kept close to ambienttemperature by contact of its large exposed surface in the chamber 9with the pumped air. The surface area of the plunger which is in contactwith the pumped air and with the lubricant in the chambers 9, 10respectively is much greater than the surface area confined within thebores of the collar 8 and of the end wall 11 in most operative positionsof the plunger, and is not substantially smaller than the confinedsurface in the thermally most unfavorable position at the end of thesuction stroke shown in FIG. 3.

The pump of the invention illustrated in FIG. 3 differs from theembodiment described in detail hereinabove by a cylinder 2' lacking anintake port, and by a cylinder head 1' having two check valves 5, 5',the latter being biased by a spring 7' to block a second bore 6' in thehead 1 during the discharge stroke only, while opening the bore 6'during the intake stroke.

It will be understood that the bores 6 of both illustrated embodimentsare normally connected to nozzles positioned to propel a weft threadthrough the shed of the loom, as is conventional. The volume of the airblast can be adjusted by means of the nut 19, and its velocity by meansof the bushing 17 and by suitable selection of the spring 7. The spring7' need only be strong enough to balance the force of gravity acting onthe valve 5'. The lubricant pressure in the chamber 10 should be higherunder all operating conditions than ambient atmospheric pressure and ispreferably never significantly lower than the maximum pressureprevailing in the working chamber 9 of the pump.

FIG. 3 illustrates only one of the many variations in the pumpillustrated in FIGS. 1 and 2 which will readily suggest themselves tothose skilled in the art, and which do not materially affect the mode ofoperation of the apparatus described in more detail, nor the advantagesthereof.

I claim:

1. A reciprocating pump comprising, in combination:

(a) a cylinder defining a cavity therein and having an axis;

(b) a collar having a central bore and axially dividing said cavity intotwo chambers connected by said bore, the cylinder having an end wallspaced from said collar, said end wall axially bounding one of saidchambers and being formed with an axial bore therethrough;

(c) a plunger conformingly received in said bores for axial slidingmovement, the plunger having a terminal axial end portion exposed in theother one of said chambers and a free axial end portion extendingoutside said cavity;

((1) a radial aperture formed in said collar and having a first orificein said axial bore and a second orifice exterior of said cylinder, saidterminal portion of said plunger normally obstructing said firstorifice;

(e) drive means for reciprocating said plunger in said cylinder inwardand outward of said other chamber, whereby the contents of said otherchamber alternatingly compressed and expanded and to move said plungerfrom said other chamber to clear said first orifice for admitting afluid under suction to other chamber;

(12') discharge valve means on said cylinder, said discharge valve meansbeing normally closed and opening in response to inward movement of saidplunger into said other chamber for releasing fluid from said otherchamber; and

(g) lubricating means for feeding a lubricant to said one chamber.

2. A pump as set forth in claim 1, wherein the area of the surface ofsaid plunger exposed in said chambers in any operating position of saidplunger during the reciprocating movement of the same is notsubstantially smaller than the area of the surface of the plungersimultaneously confined in said bores.

3. A pump as set forth in claim 2, wherein said exposed area issubstantially greater than said confined area in at least one of saidoperating positions of the plunger.

4. A pump as set forth in claim 3, wherein the axial length of saidexposed surface is substantially greater than the axial length of theconfined surface in said one operating position, said plunger in alloperating positions thereof defining in said other chamber an annularspace with an inner axial wall of said cylinder.

5. A pump as set forth in claim 4, further comprising a lubricant havinga viscosity substantially greater than that of water and filling saidannular space, and means for maintaining in said lubricant a pressurehigher than atmospheric pressure.

6. A pump as set forth in claim 1, wherein the axial length of each ofsaid chambers is substantially greater than the axial length of saidcentral bore.

7. A reciprocating pump comprising, in combination:

(a) a cylinder defining a cavity therein and having an axis;

(b) a collar having a central bore and axially dividing said cavity intotwo chambers connected by said bore, the cylinder having an end wallspaced from said collar, said end wall axially bounding one of saidchambers and being formed with an axial bore therethrough;

(c) a plunger conformingly received in said bores for axial slidingmovement, the plunger having two free axial end portions respectivelyexposed in the other one of said chambers and outside said cavity;

((1) drive means for reciprocating said plunger in said cylinder inwardand outward of said other chamber, whereby the contents of said otherchamber are alternatingly compressed and expanded, said drive meansincluding a drive member, a spring biasing said plunger inward of saidother chamber, means for continuously rotating said drive member, andmotion transmitting means interposed between said drive member and saidplunger for cyclically moving said plunger outward of said other chamberagainst the restraint of said spring, and for thereby stressing saidspring, for thereafter releasing said plunger for movement inward ofsaid other chamber under the force of said spring, when said drivemember is rotated;

(e) suction valve means on said cylinder, said valve means beingnormally closed and opening in response to outward movement of saidplunger from said other chamber for admitting a fluid to said otherchamber;

(f) discharge valve means on said cylinder, said discharge valve meansbeing normally closed and opening in response to inward movement of saidplunger into said other chamber for releasing fluid from other chamber;and

(g) lubricating means for feeding a lubricant to said one chamber.

1/1936 France 103--153 7/1965 Switzerland 103153 4/1956 Sweden 103153HENRY F. RADUAZO, Primary Examiner US. Cl. X.R.

